Keyboard assembly optimized for a mobile device

ABSTRACT

A keyboard assembly for a mobile device is provided that reduces the separation between keys by reducing the number of required dome switches. A reduction in the number of dome switches can alternatively reduce the amount of real estate taken up by dome switches on a printed circuit board (PCB). Fewer dome switches than keys are provided on a PCB to activate a desired functionality when a key is depressed. The dome switches are each actuatable by and disposed between more than one key, such keys preferably being adjacent keys. Each key has an actuator with at least one arm for actuating a dome switch in an actuated dome switch pattern when the key is depressed. Such a keyboard assembly can be used for any electronic device having a standard QWERTY or Dvorak keyboard layout, a standard telephone or numeric keypad layout, or any other layout of keys.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/302,242 filed on Nov. 21, 2002 now U.S. Pat. No. 6,891,529 entitled“Keyboard Assembly For A Mobile Device,” which claims the benefit ofpriority from U.S. patent application Ser. No. 60/331,999 filed on Nov.23, 2001. These prior applications, including the entire writtendescriptions and drawing figures, are hereby incorporated into thepresent application by reference.

FIELD OF THE INVENTION

The present invention relates to the field of keyboards and keypads forelectronic devices, in particular for mobile devices.

BACKGROUND OF THE INVENTION

Many mobile devices, such as cellular telephones, personal digitalassistants (PDAs), and other handheld computing and communicatingdevices, advantageously employ a keyboard or keypad as a means ofinputting data into the device.

Existing keyboards or keypads for small handheld devices often include astandard 12-key telephone keypad. Typing text using such a keypadrequires the user to input data in an unfamiliar manner. Other kinds ofkeyboards follow the standard Dvorak keyboard layout or, more commonly,the QWERTY keyboard layout and are used in portable handheld devicessuch as the RIM 950 Wireless Handheld™. This kind of keyboard, whenadapted to a mobile device, uses a plurality of small individual keysoptimised for operation with the thumbs of the user.

However, such a keyboard has considerably more keys than a standardtelephone keypad and the larger number of individual keys requires morespace on a printed circuit board (PCB) than a keypad. Each key requiresits own footprint and switch, such as a dome switch, on the PCB thatactivates a function or input when a key is depressed. Because of therelatively small size of such handheld devices, PCB space is limited anda QWERTY or Dvorak type keyboard takes up valuable real estate on thePCB. Keyboard size is limited by the distance between the dome switches,which have a minimum distance between them. The cost of dome switches isnot insignificant when a keyboard includes a large number of keys. It istherefore desirable to provide an improved keyboard assembly for anelectronic device.

SUMMARY OF THE INVENTION

It is an object of the present invention to obviate or mitigate at leastone disadvantage of previous keyboard assemblies for electronic devices,particularly those provided for use with mobile devices.

In one aspect of the invention, a keyboard assembly having a pluralityof keys and a plurality of dome switches, less in number than the keys,is arranged so as to reduce the separation between the keys. A reductionin the number of required dome switches can alternatively reduce theamount of real estate taken up by dome switches on a printed circuitboard.

According to an aspect of the present invention, there is provided akeyboard assembly for an electronic device having a printed circuitboard. The keyboard assembly comprises a plurality of dome switchesdisposed on the printed circuit board, and a plurality of keys, greaterin number than the plurality of dome switches. Each key is for actuatingat least one of the dome switches in an actuated dome switch pattern,the actuated dome switch pattern determining an actuated key. At leastone of the keys is for actuating more than one of the dome switches.

In a presently preferred embodiment, the electronic device is a mobiledevice.

The keyboard assembly can further comprise a plurality of actuators.Each of the actuators is associated with one of the keys. Each actuatoris for actuating a dome switch in response to depression of one of thekeys. An actuator can have at least two arms, each arm for actuating adifferent dome switch in the actuated dome switch pattern. An actuatorcan also include an arm for maintaining the balance of a key when it isdepressed.

The keys can be arranged in rows and the dome switches can be arrangedin rows between the rows of keys such that each of the dome switches ispositioned between two adjacent keys in a row, and preferably betweenfour diagonally adjacent keys disposed in two adjacent rows. Each of thedome switches is actuatable by more than one of the keys, preferably byfour diagonally adjacent keys. Each of the actuators can be moulded aspart of its associated key.

A switch activation force is applied to a switch in response to a keyactivation force in order to activate the switch. The key activationforce can be mechanically or electrically controlled or regulated, by asuitable control means, independently of the switch activation force. Assuch, a regulated key activation force can be used to ensure a commonactivation force for any key activation.

According to another aspect of the present invention, there is provideda mobile device having a memory and a printed circuit board. The mobiledevice has a keyboard assembly, which comprises a plurality of domeswitches disposed on the printed circuit board, and a plurality of keys,greater in number than the plurality of dome switches. The keys arearranged in a key configuration, each key for actuating at least one ofthe dome switches in an actuated dome switch pattern in response todepression of the key, the actuated dome switch pattern determining anactuated key. At least one of the keys is for actuating more than one ofthe dome switches. The mobile device also includes an operating systemstored in the memory, the operating system determining the actuated keybased on the actuated dome switch pattern. The mobile device furtherincludes an interface for communication between the keyboard assemblyand the operating system.

The mobile device can have different key configurations, such as: aQWERTY keyboard configuration; a Dvorak keyboard configuration; or astandard telephone keypad configuration.

According to a further aspect of the invention, there is provided akeyboard assembly for a mobile device having a printed circuit board.The keyboard assembly comprises a plurality of keys arranged in rows ina key configuration, and a plurality of dome switches, less in numberthan the plurality of keys. The dome switches are disposed on theprinted circuit board and arranged in rows between the rows of keys suchthat each of the dome switches is positioned between two adjacent keysin a row. The keyboard assembly also comprises a plurality of actuatorseach associated with one of the keys. At least one of the actuators hasat least two arms, each arm for actuating a different dome switch in anactuated dome switch pattern in response to depression of an actuatedkey.

In the keyboard assembly described above, the actuated dome switchpattern can correspond uniquely to a particular key depression. Aparticular actuator can include an arm for maintaining the balance of akey when it is depressed. Each of the dome switches can be positionedbetween four diagonally adjacent keys disposed in two adjacent rows.Each of the dome switches can be actuatable by more than one of thekeys, preferably by four diagonally adjacent keys. Each of the actuatorscan be moulded as part of its associated key.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the attached figures, wherein:

FIG. 1 illustrates a front elevation of a mobile device having akeyboard;

FIG. 2 illustrates a side view of a keyboard assembly according to afirst embodiment of the present invention;

FIG. 3 illustrates a side view of a keyboard assembly according to asecond embodiment of the present invention;

FIG. 4 illustrates a top view of a keyboard assembly according to athird embodiment of the present invention with different layers shown indashed lines; and

FIG. 5 illustrates a top view of a keyboard assembly according to afourth embodiment of the present invention with different layers shownin dashed lines.

DETAILED DESCRIPTION

Generally, the present invention provides a keyboard assembly for amobile device that reduces the separation between keys by reducing thenumber of required dome switches. A reduction in the number of domeswitches can alternatively reduce the amount of real estate taken up bydome switches on a printed circuit board (PCB). Fewer dome switches thankeys are provided on a PCB to activate a desired functionality when akey is depressed. The dome switches are each actuatable by and disposedbetween more than one key, such keys preferably being adjacent keys.Each key has an actuator with at least one arm for actuating a domeswitch in an actuated dome switch pattern when the key is depressed.Such a keyboard assembly can be used for any electronic device having astandard QWERTY or Dvorak keyboard layout, a standard telephone ornumeric keypad layout, or any other layout of keys.

FIG. 1 illustrates a front elevation of an electronic device having akeyboard. Keyboard assemblies according to embodiments of the presentinvention can be used with, and incorporated in, such an electronicdevice 20. Although the device 20 shown in FIG. 1 is a mobile electronicdevice having a keyboard, aspects of the present invention can beadvantageously incorporated in any type of electronic device having anytype of key configuration. The term key configuration is used herein torepresent any configuration of keyboard or keypad, including but notlimited to: QWERTY keyboard layout; Dvorak keyboard layout; standardtelephone keypad layout; and any other configuration incorporating oneof these layouts or portions thereof. Similarly, the term keyboard asused herein generally refers to any plurality of keys arranged in akeyboard or keypad configuration or layout.

The device 20 typically has a housing 22, a display 24, such as a liquidcrystal display (LCD), and a keyboard area having a keyboard 26 arrangedin a key configuration. The keyboard 26 is typically situated adjacentto the display 24 and preferably below the display. The keyboardcomprises a plurality of keys 28 arranged in a key configuration. Thesekeys can typically be positioned to form a QWERTY keyboard or a Dvorakkeyboard.

FIG. 2 illustrates a side view of a keyboard assembly 200 according to afirst embodiment of the present invention. The term keyboard assembly isused herein to describe the collection of physical components thattogether allow a device to accept user inputs via a plurality of keys.These physical components can include, but are not limited to: keys,actuators, dome switches, and a printed circuit board.

Keys 202, 204 and 206 preferably protrude through openings 28 in thedevice housing 22. Although only three keys are shown in FIG. 2 forsimplicity of illustration and explanation, it will be apparent to oneskilled in the art that a keyboard can include many more such keys. Eachkey actuates an input or function when a user depresses the key, therebydepressing at least one dome switch 222, 224, each of which is disposedon a printed circuit board (PCB) 240. Conventionally, each key isassociated with an individual dome switch. According to the presentinvention, each key is associated with one or more dome switches, andeach dome switch is associated with one or more keys. In the embodimentillustrated in FIG. 2, two dome switches 222 and 224 are associated withthree adjacent keys 202, 204 and 206.

Typically, each key in a keyboard for an electronic device has anactuator, or post, underneath the key. The actuator engages or actuatesa dome switch. Each actuator has at least one arm for actuating a domeswitch in response to depression of a key. In this embodiment, keys 202,204 and 206 preferably have actuators 252, 254, 256 respectivelyassociated therewith. Each of the actuators 252, 254 and 256 has atleast one arm that actuates one or more of the dome switches 222, 224.For instance, when the key 202 is depressed, the actuator 252 actuatesthe dome switch 222 via arm 262. When the key 204 is depressed, theactuator 254 actuates both the dome switches 222 and 224 via arms 264and 274, respectively. When the key 206 is depressed, the actuator 256actuates the dome switch 224 via arm 266.

It can therefore be seen that depressing a particular key results in anactuated dome switch pattern. The actuated dome switch pattern comprisesan identification of the dome switches that are actuated in response todepressing a particular key. This actuated dome switch pattern is not atemporal or sequential pattern of dome switch actuation; rather, itcomprises a pattern of dome switches that are actuated simultaneously,substantially at the same time, or within a predetermined window oftime. Based on the actuated dome switch pattern, it can be determinedwhich key is actuated. Each dome switch pattern preferably correspondsuniquely to a particular key depression.

In relation to FIG. 2, a dome switch pattern where only the dome switch222 is actuated is caused by depression of the key 202, which depressesthe arm 262 of the actuator 252. Similarly, a dome switch pattern whereboth the dome switches 222 and 224 are actuated is caused by depressionof the key 204, which depresses the arms 264 and 274 of the actuator254. Finally, a dome switch pattern where only the dome switch 224 isactuated is caused by depression of the key 206, which depresses the arm266 of the actuator 256.

When a keyboard assembly such as the one illustrated in FIG. 2 is usedin an electronic device, such as a mobile device, the device typicallyhas an operating system stored in its memory. When a key is depressed,the resulting actuated dome switch pattern is recognized by the device'soperating system as being uniquely associated with depression of aparticular key. This can be accomplished, for example, by storing inmemory information regarding each possible key depression and itscorresponding actuated dome switch pattern. This can be advantageouslybe stored in a type of lookup table in the device's memory, or can bealternatively accomplished by any other equivalent means.

A keyboard assembly such as the one described above allows the keys thatprotrude from the device housing to be spaced closer together than withconventional keyboard arrangements. In this example, the spacing isdetermined according to the distance required for three keys to be ableto engage two dome switches on the PCB. Alternatively, the presentinvention results in less real estate on the PCB being devoted to thedome switches, thus making space for other components. Of course, theseconcepts can be expanded to a plurality of such key and dome switchcombinations, in various rows of keys. Examples of such combinationswill be discussed in relation to further embodiments of the inventiondiscussed below. In an alternative embodiment, each of the actuators canbe moulded as part of the key. The keys can be made of plastic and canbe set in a plastic web. The actuators can be made of plastic.

A switch activation force is applied to a switch in response to a keyactivation force in order to activate the switch. The key activationforce can be mechanically or electrically controlled or regulated, by asuitable control means, independently of the switch activation force. Assuch, a regulated key activation force can be used to ensure a commonactivation force for any key activation.

FIG. 3 illustrates a side view of a keyboard assembly 300 according to asecond embodiment of the present invention. The embodiment in FIG. 3 issimilar to that illustrated in FIG. 2 in the layout of keys 302, 304,306 and of dome switches 322 and 324 on PCB 340. The embodiment in FIG.3 provides for a different design of an actuator used in conjunctionwith an end key, i.e. a key that is at an end of a row of keys.Actuators 352 and 356 in FIG. 3, in addition to having arms 362 and 366for actuating the dome switches 322 and 324, respectively, also havearms 372 and 376. Each of the arms 372 and 376 does not engage a domeswitch, but maintains the balance of the key when it is depressed. Anyof the actuators 352, 354 and 356 can alternatively comprise one or moreadditional arms for actuating further dome switches on adjacenthorizontal or vertical rows. Any of these actuators can furtheralternatively comprise one or more additional arms that does not engagea dome switch, but maintains the balance of the key when it isdepressed.

FIG. 4 illustrates a top view of a keyboard assembly 400 according to athird embodiment of the present invention with different layers shown indashed lines. In this embodiment, keys are laid out in rows and domeswitches are laid out in rows between the rows of keys such that thedome switches are positioned between two adjacent keys in a row. A domeswitch is then preferably associated with four diagonally adjacent keys.Although a PCB is not illustrated in FIG. 4, it is to be understood thatthe keyboard arrangement 400 includes a PCB on which the dome switchesare disposed. Although actuators and dome switches are both illustratedin dashed lines, it is to be understood that these two sets of elementsare themselves on different layers, each different from the key layer.Three different types of key and actuator arrangements will now bedescribed in relation to the embodiment illustrated in FIG. 4.

A key 402 in a top right corner of the keyboard assembly 400 is arrangedso as to actuate only one dome switch when it is depressed. The key 402preferably has an actuator 452 having an arm 462 that extends diagonallyfrom the key. The arm 462 actuates an adjacent dome switch 422 when thekey 402 is depressed. A key and actuator pair at the bottom right cornerof the keyboard assembly 400 has a similar structure to the key 402 andthe actuator 452. An actuator associated with such a key canalternatively comprise one or more additional arms that do not engage adome switch, but maintain the balance of the key when it is depressed.

An edge key 454 being at an outer edge of a key configuration preferablyhas an actuator 454 having two arms 464 and 474 for actuating twodiagonally adjacent dome switches 422 and 424, situated above and belowthe key 404, when the key 404 is depressed. Similarly, a key 406 in thetop row preferably has an actuator 456 having two arms 466 and 476 foractuating two diagonally adjacent dome switches 422 and 426, situatedbelow the key 406, when the key 406 is depressed. Other key and actuatorpairs in the top and bottom rows have a similar structure to the key 406and the actuator 456 for actuating two diagonally adjacent dome switchesin a row either above or below the key. This includes the key andactuator pairs in the top left and bottom left corners of the keyboardassembly 400. Also, an actuator associated with such a key canalternatively comprise one or more additional arms that do not engage adome switch, but maintain the balance of the key when it is depressed.

A key 408 in a middle row preferably has an actuator 458. The actuator458 has four arms 468, 478, 488 and 498 for actuating four diagonallyadjacent dome switches 422, 424, 426 and 428, above and below the key408. Other key and actuator pairs in any row that is not a top or bottomrow can have a similar structure to the key 408 and the actuator 458.This includes a key and actuator pair at the left edge, or end, of themiddle row of FIG. 4, and applies to any other such middle row that maybe present in a key configuration. Actuators are preferably made fromplastic and can be moulded within the shape of the key.

With particular reference to FIG. 4, an actuated dome switch patternwhere only the dome switch 422 is actuated is interpreted as being aresult of the key 402 being depressed. An actuated dome switch patternwhere the dome switches 422 and 424 are actuated is interpreted as beinga result of the key 404 being depressed. An actuated dome switch patternwhere the dome switches 422 and 426 are actuated is interpreted as beinga result of the key 406 being depressed. Also, an actuated dome switchpattern where the dome switches 422, 424, 426 and 428 are actuated isinterpreted as being a result of the key 408 being depressed. Theoperating system is able to interpret other actuated dome switchpatterns as preferably being uniquely the result of a particular keybeing depressed.

The keyboard assemblies in the embodiments discussed above are notlimited to mobile devices. These types of keyboard assemblies can beimplemented in any electronic device that requires a QWERTY or Dvorakkeyboard, or any similar keyboard configuration. Some examples includepersonal computer (PC) keyboards and label makers.

FIG. 5 illustrates a top view of a keyboard assembly 500 according to afourth embodiment of the present invention with different layers shownin dashed lines. FIG. 5 is an embodiment that is particularly suited foruse with a key configuration such as a numeric keypad, or a standardtelephone keypad. Although a PCB is not illustrated in FIG. 5, it is tobe understood that the keyboard assembly 500 includes a PCB on which thedome switches are disposed. Although actuators and dome switches areboth illustrated in dashed lines, it is to be understood that these twosets of elements are themselves on different layers, each different fromthe key layer.

In FIG. 5, the key configuration has less dome switches than keys, sinceeach dome switch is associated with more than one key. As in FIG. 4, inthis embodiment, preferably each dome switch is associated with fourdifferent keys. In this embodiment, an actuator actuates at least oneand at most four dome switches in a similar manner as in FIG. 4. Anexemplary key 502 has an actuator 552 that has at least one arm 562 foractuating a dome switch 522. Different types of key and actuator pairs,as discussed in relation to FIG. 4, are similarly present in theembodiment shown in FIG. 5.

An electronic device incorporating a keyboard assembly such asillustrated in FIG. 3, FIG.4 or FIG. 5 preferably has an operatingsystem stored in memory. When a key is depressed, the resulting actuateddome switch pattern is recognized by the device's operating system aspreferably being uniquely associated with depression of a particularkey. This can be accomplished, for example, by storing in memoryinformation regarding each possible key depression and its correspondingactuated dome switch pattern. This can advantageously be stored in atype of lookup table in the device's memory, or can be alternativelyaccomplished by any other equivalent means.

A key configuration such as the one illustrated in FIG. 5 is not limitedto use in mobile devices, but could be used in any electronic devicethat requires a numeric keypad. Some examples of such devices includemobile phones, standard telephones, calculators, and alarm systems.

The above-described embodiments of the present invention are intended tobe examples only. Alterations, modifications and variations may beeffected to the particular embodiments by those of skill in the artwithout departing from the scope of the invention, which is definedsolely by the claims appended hereto.

1. A keyboard assembly for an electronic device having a printed circuitboard, comprising: a plurality of dome switches disposed on the printedcircuit board; and a plurality of keys, greater in number than theplurality of dome switches, each key for actuating at least one of theplurality of dome switches in an actuated dome switch pattern, theactuated dome switch pattern determining an actuated key, and at leastone of the plurality of keys for actuating more than one of theplurality of dome switches simultaneously; and a plurality of actuators,each of the plurality of actuators associated with one of the pluralityof keys for actuating one of the plurality of dome switches in responseto depression of the one of the plurality of keys; wherein a particularactuator includes an arm for maintaining the balance of a key when it isdepressed.
 2. A keyboard assembly according to claim 1 wherein theelectronic device is a mobile device.
 3. A keyboard assembly accordingto claim 1 wherein at least one of the plurality of actuators has atleast two arms, each arm for actuating a different one of the pluralityof dome switches in the actuated dome switch pattern.
 4. A keyboardassembly according to claim 1 wherein the plurality of keys are arrangedin rows and the plurality of dome switches are arranged in rows betweenthe rows of keys such that each of the plurality of dome switches ispositioned between two adjacent keys in a row.
 5. A keyboard assemblyaccording to claim 1 wherein each of the plurality of dome switches ispositioned between four diagonally adjacent keys disposed in twoadjacent rows.
 6. A keyboard assembly according to claim 1 wherein eachof the plurality of dome switches is actuatable by more than one of theplurality of keys.
 7. A keyboard assembly according to claim 1 whereineach of the plurality of dome switches is actuatable by four diagonallyadjacent keys.
 8. A keyboard assembly according to claim 1 wherein eachof the plurality of actuators is moulded as part of its associated key.9. A mobile device having a memory and a printed circuit board,comprising: a keyboard assembly including: a plurality of dome switchesdisposed on the printed circuit board; a plurality of keys, greater innumber than the plurality of dome switches, arranged in a keyconfiguration, each key for actuating at least one of the plurality ofdome switches in an actuated dome switch pattern in response todepression of the key, the actuated dome switch pattern determining anactuated key, and at least one of the plurality of keys for actuatingmore than one of the plurality of dome switches simultaneous; aplurality of actuators, each of the plurality of actuators associatedwith one of the plurality of keys for actuating one of the plurality ofdome switches in response to depression of the one of the plurality ofkeys, wherein a particular actuator includes an arm for maintaining thebalance of a key when it is depressed; an operating system stored in thememory, the operating system determining the actuated key based on theactuated dome switch pattern; and an interface for communication betweenthe keyboard assembly and the operating system.
 10. A mobile deviceaccording to claim 9 wherein the key configuration comprises a QWERTYkeyboard configuration.
 11. A mobile device according to claim 9 whereinthe key configuration comprises a Dvorak keyboard configuration.
 12. Amobile device according to claim 9 wherein the key configurationcomprises a standard telephone keypad configuration.